Recently, research and development efforts have been made on an apparatus using multiple cameras mainly used for surveillance. For usage purposes, the apparatus must meet two requirements for an imaging target zone comprising a surveillance target zone:
first, to provide constant surveillance of the imaging target zone with no blind spots and to detect a target within the zone, and
second, the requirement is to obtain detailed information on the detection target present within the imaging target zone.
The conventional apparatus using multiple cameras self-adjusts the imaging zone of each camera to meet the two requirements. Such conventional apparatuses using multiple cameras are represented in Patent References 1 and 2.
First, the conventional apparatus referred to in Patent Reference 1 is described. FIG. 1 illustrates the apparatus of the first conventional art described in Patent Reference 1 that self-adjusts camera imaging zones. With the detection camera apparatus 10010 of FIG. 1, a camera 10011 and a reflection mirror 10012 capture a detection target image throughout an extensive imaging zone, a moving object extractor 10013 extracts the detection target in the captured image, and a positional information extractor 10014 extracts the positional information of the detection target. Thus, the detection camera apparatus 10010 obtains the positional information of the detection target throughout the extensive imaging zone. With evaluation camera apparatus 10020, a camera controller 10022 controls the rotation and depression angles and zoom rate of a camera 10021 based on the positional information of the detection target, and the evaluation camera apparatus 10020 captures an enlarged image of the detection target. Thus, the evaluation camera apparatus 10020 obtains detailed information of the detection target.
FIG. 2 is a drawing showing the imaging zones of the detection camera apparatus 10010 and evaluation camera apparatus 10020. In the figure, the black circles indicate the positions where the detection camera apparatuses 10110 comprising fixed cameras are installed, of which the circles or hexagons indicate the imaging zones. When, as shown in the figure, the detection camera apparatuses 10110 are artificially installed on a regular basis, the imaging target zone or surveillance target zone can be constantly detected with no blind spots.
A conventional apparatus referred to in Patent Reference 2 is described hereafter. FIG. 3 illustrates the second conventional apparatus described in Patent Reference 2 that self-adjusts the camera imaging zones. In FIG. 3, a moving object detection camera 10211 intended to capture an image of a detection target throughout an extensive imaging zone changes one's own imaging zone using an orientation control means 10212, and a surveillance camera 10221 intended to capture an enlarged image of the detection target changes one's own imaging zone using an orientation control means 10222. The imaging zone of each camera is determined based on information previously stored in a camera field angle memory means 10231 and a camera field angle memory means 10232 using the position of a detection target extracted in the image captured by the moving object detection camera 10211 and the imaging zone of each camera in an image processing apparatus 10240.
How the imaging zone of each camera is determined is further described next. FIGS. 4, 5, and 6 are illustrations explaining how the imaging zone of each camera is determined in the second conventional art, illustrating images captured by the moving object detection camera 10211 and dividing them into several block images. First, the imaging zone of the moving object detection camera 10211 is determined as follows. When a detection target is present in the shaded blocks of FIG. 4, the orientation of the moving object detection camera 10211 is changed in the direction of the arrows in each of the blocks of FIG. 54 corresponding to FIG. 4, respectively, thereby changing the imaging zone of the camera. The imaging zone of the moving object detection camera 10211 corresponding to each block position is manually pre-determined and the information is pre-set in the camera field angle memory means 10231. Then, the imaging zone of the surveillance camera 10221 is determined as follows. When a detection target is present in the block position shown in FIG. 6, the orientation of the surveillance camera 10221 is changed to have the imaging zone indicated by the broken lines, thereby changing the imaging zone of the camera. The imaging zone of the surveillance camera 10221 corresponding to each block position is manually pre-determined and the information is pre-set in the camera field angle memory means 10232.
Characteristics of the imaging zone self-adjustment of the conventional apparatus using multiple cameras are summarized hereafter. First, each camera has a fixed, pre-determined role. Namely, it is the detection camera apparatus 10010 in the conventional apparatus referred to in Patent Reference 1 and the moving object detection camera 10211 in the conventional apparatus referred to in Patent Reference 2 that plays the role of detecting a detection target throughout an extensive imaging zone and it is the evaluation camera apparatus 10020 in the conventional apparatus referred to in Patent Reference 1 and the surveillance camera 10211 in the conventional apparatus referred to in Patent Reference 2 that plays the role of obtaining detailed information of the detection target, such as an enlarged image of the detection target. Thus, a camera playing one role achieves the first requirement and a camera playing the other role achieves the second requirement (the first characteristic of the conventional art).
In the conventional apparatus referred to in Patent Reference 2, for example, the imaging zone of the moving object detection camera 10211 is changed to the detection zone shifted to the top left shown as the top left block of FIG. 54 according to the change in the situation, in that a detection target is present in the top left block of the FIG. 4. Thus, the imaging zone of each camera is determined and adjusted based on information in the form of a table containing situational changes predicted and manually created and imaging zones corresponding thereto on a one-to-one basis (the second characteristic of the conventional art).
The conventional apparatus referred to in Patent Reference 1 uses manually pre-placed fixed cameras on a regular basis in order to achieve the first requirement (the third characteristic of the conventional art).
The self-adjustment of the imaging zone of the conventional apparatus using multiple cameras is described above. Self-adjustment of the imaging zone of the conventional apparatus using a single camera is described hereafter. An apparatus using a single camera and self-adjustment the imaging zone of the camera is described in Patent Reference 3. Patent Reference 3 discloses two techniques, known as “auto-scanning” and “auto-panning” as a means for self-adjustment the imaging zone of a camera.
First, the “auto-scanning” technique is described. FIG. 8 is a drawing explaining the “auto-scanning” technique according to the third conventional art. The “auto-scanning” technique allows a camera 10701 to sequentially automatically image multiple imaging zones from a first imaging zone 10711 to an n-th imaging zone 1071N shown in the figure. Imaging zone information of the first imaging zone 10711 to the n-th imaging zone 1071N is pre-recorded in a recording means 10703. This technique is realized by an orientation control means 10702 controlling the orientation of the camera 10701 based on the information recoded in the recording means 10703 so as to sequentially change the imaging zone of the camera 10701 from the first imaging zone 10711 to the n-th imaging zone 1071N.
The “auto-panning” technique is described hereafter. FIG. 9 is a drawing explaining the “auto-panning” technique. The “auto-panning” technique allows a camera 10801 to automatically and repeatedly pan from side to side between a first panning angle 10811 and a second panning angle 10812 shown in the figure so as to self-adjust the imaging zone of the camera 10801. Though not shown in FIG. 9, the technique is realized by mechanical switches provided for the first panning angle 10811 and second panning angle 10812 and confirm that the camera 10801 is oriented at either panning angle so that an orientation control means 10802 controls the orientation of the camera.
Characteristics of the self-adjustment of the imaging zone of the conventional apparatus using a single camera are summarized hereafter. In the conventional apparatus referred to in Patent Reference 3, for example, the imaging zone of the camera 10701 is changed based on the imaging zone information of the first imaging zone 10711 to the n-th imaging zone 1071N recorded in the recoding means 10703. Similar to the self-adjustment of the imaging zone of the apparatus using multiple cameras, the imaging zone of the camera is determined and adjusted based on information in the form of a table containing imaging zones manually predicted and created although they do not correspond to situational changes on a one-to-one basis (the second characteristic of the conventional art).    Patent Reference 1: Japanese Patent Publication No. 3043925 (FIGS. 1 and 6)    Patent Reference 2: Japanese Patent Publication No. 3180730 (FIGS. 1 and 7 to 9)    Patent Reference 3: Japanese Laid-Open Patent Application No. H01-288696
However, in the conventional apparatuses described above, the imaging zone of each camera is determined and adjusted based on information in the form of a table containing situational changes manually predicted and set up and imaging zones corresponding thereto on a one-to-one basis (the above second characteristic of the conventional art). Therefore, information in the form of a table containing situational changes and imaging zones corresponding thereto on a one-to-one basis should be manually predicted and created one by one for each camera.
The information depends on the position and size of the imaging zone, individually predicted situational changes, locations and the number of cameras. Each time a change occurs in the elements, the information should be individually recreated one by one. The work becomes complex as the number of cameras increase and its cost and workload becomes enormous. It is common that a building surveillance system will use over ten cameras.
The conventional apparatuses meet the first requirement by manually positioning fixed cameras on a regular basis (the above third characteristic of the conventional art). However, even if a single camera failure occurs, the apparatus fails to achieve the first requirement.
For example, as shown in FIG. 7, an increased number of detection camera apparatuses 10010 can be used to cover the detection target zone with no blind spots regardless of a single camera failure. However, this is no doubt inefficient.
It is an objective of the present invention to resolve the conventional art problems indicated above, and to provide an imaging zone adjusting apparatus that eliminates the necessity of manually predicting situational changes and creating a table and allows the imaging target zone to be imaged with no blind spots, even if some of the multiple cameras are unserviceable and a camera terminal constitutes the imaging zone adjusting apparatus.